This invention relates to a fault indicator circuit for a transformer coupled fault meter for use with a current carrying conductor.
Fault indicators of themselves are well-known in the art. The more recent indicators are self-contained, self-powered elements which include a split core which may be mounted about a conductor being monitored. Connected to the sensing coil on the core by a suitable conductor is the sensing circuitry and indicator. The sensing circuitry in some cases operates the transformer above its saturation level and thus diminishes its sensitivity, speed of response and temperature stability. The sensing circuit is generally mounted with the indicator within a casing. In some known installations, the indicator casing is made of Lexan plastic and surrounded by suitable sealing members. The Lexan plastic, however, has been found to permit moisture migration therethrough, and therefore, failures have occurred. As is well-known in the more recent past, electrical distribution systems, especially for residential use, have been placed underground with transformers and other distribution elements positioned in vaults embedded in the earth. These vaults tend to fill with water on occasion, and submerge the conductor and other elements in the vault. The fault indicator therefore, must be sealed against failure due to submersion. Many forms of sealing structures are known in the art.